fix and add documentation for distortion

Author: KevinGrajeda

src/distortion.js

@@ -30,10 +30,72 @@ function makeDistortionCurve(amount) {
  * @class p5.Distortion
  * @extends p5.Effect
  * @constructor
- * @param {Number} [amount=0.25] Unbounded distortion amount.
- *                                Normal values range from 0-1.
- * @param {String} [oversample='none'] 'none', '2x', or '4x'.
+ * @param {Number} [amount] Unbounded distortion amount.
+ *                                Normal values range from 0-1 (defaults to 0.25)
+ * @param {String} [oversample] 'none', '2x' (default), or '4x'.
+ *  @example
+ *  <div><code>
+ *  let osc, distortion, fft;
  *
+ *  function setup() {
+ *    let cnv = createCanvas(100, 100);
+ *    fft = new p5.FFT(0, 256);
+ *
+ *    osc = new p5.TriOsc();
+ *    osc.amp(0.3);
+ *    osc.freq(375);
+ *
+ *    distortion = new p5.Distortion();
+ *    distortion.process(osc);
+ *    cnv.mousePressed(oscStart);
+ *  }
+ *
+ *  function draw() {
+ *    background(220);
+ *    // set the amount based on mouseX
+ *    let amount = constrain(map(mouseX, 0, width, 0, 1), 0, 1);
+ *
+ *    // multiply the amount to smooth the value
+ *    distortion.set(amount * amount);
+ *
+ *    noStroke();
+ *    fill(0);
+ *    text('tap to play', 10, 20);
+ *    text('amount: ' + amount, 10, 40);
+ *
+ *    // draw the waveform
+ *    var samples = fft.waveform();
+ *    drawOscilloscope(samples);
+ *  }
+ *
+ *  //function based on distortion example
+ *  function drawOscilloscope(samples) {
+ *    var yTranslateScope = 20;
+ *    var scopeWidth = width;
+ *    var scopeHeight = height;
+ *
+ *    stroke(0);
+ *    strokeWeight(1);
+ *    noFill();
+ *
+ *    beginShape();
+ *    for (var sampleIndex in samples) {
+ *      var x = map(sampleIndex, 0, samples.length, 0, scopeWidth);
+ *      var y = map(samples[sampleIndex], -1, 1, -scopeHeight / 4, scopeHeight / 4);
+ *      vertex(x, y + scopeHeight / 2 + yTranslateScope);
+ *    }
+ *    endShape();
+ *  }
+ *
+ *  function oscStart() {
+ *    osc.start();
+ *  }
+ *
+ *  function mouseReleased() {
+ *    osc.stop();
+ *  }
+ *
+ *  </code></div>
  */
 class Distortion extends Effect {
   constructor(amount, oversample) {
@@ -62,7 +124,8 @@ class Distortion extends Effect {
      */
     this.waveShaperNode = this.ac.createWaveShaper();
 
-    this.amount = curveAmount;
+    //this.amount = curveAmount;
+    this.amount = amount;
     this.waveShaperNode.curve = makeDistortionCurve(curveAmount);
     this.waveShaperNode.oversample = oversample;
 
@@ -76,9 +139,10 @@ class Distortion extends Effect {
    *
    * @method process
    * @for p5.Distortion
-   * @param {Number} [amount=0.25] Unbounded distortion amount.
+   * @param {Object} Signal  An object that outputs audio
+   * @param {Number} [amount] Unbounded distortion amount.
    *                                Normal values range from 0-1.
-   * @param {String} [oversample='none'] 'none', '2x', or '4x'.
+   * @param {String} [oversample] 'none', '2x', or '4x'.
    */
   process(src, amount, oversample) {
     src.connect(this.input);
@@ -90,14 +154,15 @@ class Distortion extends Effect {
    *
    * @method set
    * @for p5.Distortion
-   * @param {Number} [amount=0.25] Unbounded distortion amount.
+   * @param {Number} [amount] Unbounded distortion amount.
    *                                Normal values range from 0-1.
-   * @param {String} [oversample='none'] 'none', '2x', or '4x'.
+   * @param {String} [oversample] 'none', '2x', or '4x'.
    */
   set(amount, oversample) {
-    if (amount) {
+    if (typeof amount === 'number') {
       var curveAmount = p5.prototype.map(amount, 0.0, 1.0, 0, 2000);
-      this.amount = curveAmount;
+      //this.amount = curveAmount;
+      this.amount = amount;
       this.waveShaperNode.curve = makeDistortionCurve(curveAmount);
     }
     if (oversample) {

test/tests/p5.Distortion.js

@@ -10,7 +10,7 @@ describe('p5.Distortion', function () {
     expect(distortion.waveShaperNode).to.have.property('context').to.not.be
       .null;
     //default case
-    expect(distortion.amount).to.equal(500);
+    expect(distortion.amount).to.equal(0.25);
     expect(distortion.waveShaperNode.oversample).to.equal('2x');
 
     distortion.dispose();
@@ -19,23 +19,23 @@ describe('p5.Distortion', function () {
 
   it('can be created with only amount as a parameter', function () {
     let distortion = new p5.Distortion(0.3);
-    expect(distortion.amount).to.equal(600);
+    expect(distortion.amount).to.equal(0.3);
     expect(distortion.waveShaperNode.oversample).to.equal('2x');
 
     //non-numerical value
     expect(() => new p5.Distortion('a')).to.throw();
   });
   it('can be created with only oversample as a parameter', function () {
     let distortion = new p5.Distortion(undefined, '4x');
-    expect(distortion.amount).to.equal(500);
+    expect(distortion.amount).to.equal(0.25);
     expect(distortion.waveShaperNode.oversample).to.equal('4x');
 
     //non-numerical value
     expect(() => new p5.Distortion(undefined, 500)).to.throw();
   });
   it('can be created with both parameters', function () {
     let distortion = new p5.Distortion(0.8, '4x');
-    expect(distortion.amount).to.equal(1600);
+    expect(distortion.amount).to.equal(0.8);
     expect(distortion.waveShaperNode.oversample).to.equal('4x');
   });
 
@@ -48,27 +48,27 @@ describe('p5.Distortion', function () {
 
       //both params
       distortion.process(osc, 0.62, '4x');
-      expect(distortion.amount).to.equal(1240);
+      expect(distortion.amount).to.equal(0.62);
       expect(distortion.waveShaperNode.oversample).to.equal('4x');
     });
     it('can set amount and oversample', function () {
       let distortion = new p5.Distortion();
       //only one param
       distortion.set(0.98);
-      expect(distortion.amount).to.equal(1960);
+      expect(distortion.amount).to.equal(0.98);
       expect(distortion.waveShaperNode.oversample).to.equal('2x');
       distortion.set(undefined, '4x');
-      expect(distortion.amount).to.equal(1960);
+      expect(distortion.amount).to.equal(0.98);
       expect(distortion.waveShaperNode.oversample).to.equal('4x');
 
       //both params
       distortion.set(0.14, '2x');
-      expect(distortion.amount).to.equal(280);
+      expect(distortion.amount).to.equal(0.14);
       expect(distortion.waveShaperNode.oversample).to.equal('2x');
     });
     it('can get amount', function () {
       let distortion = new p5.Distortion(0.43, '2x');
-      expect(distortion.getAmount()).to.equal(860);
+      expect(distortion.getAmount()).to.equal(0.43);
     });
     it('can get over sample', function () {
       let distortion = new p5.Distortion(0.43, '4x');